Re: [PR] MINIFICPP-2791 Fix deadlock during C2 flow update [nifi-minifi-cpp]

["Copilot (via GitHub)" <gi...@apache.org>]

Copilot commented on code in PR #2163:
URL: https://github.com/apache/nifi-minifi-cpp/pull/2163#discussion_r3181341115


##########
libminifi/src/FlowController.cpp:
##########
@@ -130,6 +131,10 @@ nonstd::expected<void, std::string> FlowController::applyConfiguration(const std
     std::lock_guard<std::recursive_mutex> flow_lock(mutex_);
     stop();
 
+    // Clear the controller services now that all timer callback threads have been stopped
+    clearControllerServices();
+    controller_service_provider_impl_ = flow_configuration_->getControllerServiceProvider();

Review Comment:
   This change is addressing a deadlock/race between flow reload and the onSchedule retry timer, but there doesn’t appear to be a regression test that exercises a flow update while the retry timer is active (e.g., a processor repeatedly failing onSchedule with administrative yield enabled, then calling applyConfiguration). Adding a test that would previously hang and now completes would help prevent future reintroductions.



##########
libminifi/src/FlowController.cpp:
##########
@@ -110,7 +110,8 @@ FlowController::~FlowController() {
 nonstd::expected<void, std::string> FlowController::applyConfiguration(const std::string &source, const std::string &configurePayload, const std::optional<std::string>& flow_id) {
   std::unique_ptr<core::ProcessGroup> newRoot;
   try {
-    newRoot = updateFromPayload(source, configurePayload, flow_id);
+    // Parse the new flow here and and clear controller services later to avoid race condition with the onScheduleTimer_ callback thread

Review Comment:
   Typo/grammar in the new comment: "here and and" has a duplicated word, and it reads awkwardly (also missing article before "race condition"). Please fix the comment text so it’s clear and correct.
   



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